It is running incredibly slowly, so I tried changing it from segregated to coupled to see if that changed anything. Then this crashed, giving me a "floating point exception" error. It seems to me that currently this is a fairly simple simulation. I havent even put conditions on to make suction occur yet.

I am getting huge recirculations within the flow, as you can see from my attached picture.

Switching to the coupled solver isn't going to make anything better (it's more unstable than the segregated solver and takes longer to solve).

Whenever you use ideal gas, temperature is usually the culprit. The solver is solving for the fluid temperature which affects the density and messes a lot of things up. It is better if you can remove this dependency. I always recommend using constant density instead of ideal gas. Do you even need to use the ideal gas model? Is the incompressible (constant density) gas more appropriate?

Regardless of whether you are using ideal gas / constant density the energy equation takes a long time to solve! I always try to freeze the energy solver whenever possible because of how long it takes.